Fire control



June 16, 1942. H. N. DURHAM ETAL FIRE CONTROL Filed D80. 15, 1937 2Sheets-Sheet 1 b am ATTORNEY June 16; 1942. DURHAM ETAL 2,28%,474

FIRE CONTROL Filed Dec. 15, 1937 2 Sheets-Sheet 2 ATTORNEY Patented June16, 1942 FIRE CONTROL Hobart N. Durham, Munsey Park, N. Y., and GeorgeB. Finnegan, Jr., Mountain Lakes,

Application December 15, 1937, Serial No. 179,896

9 Claims.

The present invention relates to fire control and more particularly to anovel and useful fire control device for artillery firing at aerial andother moving targets.

Objects and advantages of the invention will be set forth in parthereinafter and in part will be obvious herefrom, or may be learned bypractice with the invention, the same being realized and attained bymeans of the instrumentali ties and combinations pointed out in theappended claims.

The invention consists in the novel parts, constructions, arrangements,combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a parthereof, illustrate one embodiment of the invention, and, together withthe description, serve to explain the principles of the invention.

Of the drawings:

Fig. 1 is a schematic view showing diagrammatically the arrangement ofthe various parts of the anti-aircraft fire control apparatus inaccordance with the present preferred embodiment of the invention;

Fig. 2 is a front elevation of an illustrative embodiment of one of thefire observing instruments used in the embodiment of Fig. 1;

Fig. 3 is a section on line 3-3 of Fig. 2 with the fire observinginstrument shown applied to the head of an observer;

Fig. 4 is a horizontal section on line 4-& of Fig. 2;

Fig. 5 is a vertical section on line 55 of Fig.

Fig. 6 is a fragmentary detailed elevation of the forehead adjustingmeans;

Fig. 7 is a vertical section on line 1-1 of Fig. 4; and

Fig. 8 is a detail in elevation of the main plate of the supportingframe.

The present invention is, in certain respects, an improvement upon theanti-aircraft fire-control method and apparatus shown and described inthe patent of Grayson Schmidt 2,157,575, May 9, 1939. In other respectsthe invention comprises certain subje-ct matter disclosed, but notclaimed in said application of Grayson Schmidt". The present inventionhas for its object the provision of a novel and improved anti-aircraftfire control apparatus and method, applicable to firing of projectileswhich are visible during at least a part of their trajectory by whichthe accuracy of fire at a moving aerial target, such as an airplane, canbe improved. A further object is the provision of a novel and improvedantiaircraft fire control device which can be used with ease and willgive to both the gunner and a flank observer an accurate indication ofwhen the visible projectile is at the range of the target so that thetrue deviations of the projectile from the target are made apparent andthe approciate corrections may be made in the firing of the gun forfuture shots. Still another object of the invention is the provision ofan improved fire observing instrument which will enable the gunner andflank observer to ascertain the position of the projectilesimultaneously and with the greatest degree of accuracy.

In accordance with the present embodiment of the invention, the flankobserver and gunner both observe the trajectory of a tracer bullet, orother visible projectile, as it is moving towards its target and whenthe flank observer appears to see the bullet at the range of the planeor other target a visual indication is given to the gunner under thecontrol of the flank observer, so that the gunner may ascertain the truedeviation of the projectile and correct his aim to cause the next bulletand succeeding bullets to come closer and closer to the target. Thisvisual indication is given by means of a change in color of the imageobserved by the gunner and preferably also by the flank observer. Thus,the flank observer and gunner are able to see and follow the tracerbullet and target during the entire travel of the bullet, and thisvision is not interrupted at any time either before, during or after thegiving of the signal. Specifically, the gunner and flank observer Viewthe travel of the tracer bullet through a color filter which ismomentarily removed from the path of vision during the giving of thesignal, so that the bullet appears of a different color at that moment,and thus the gunner can distinctly visualize and ascertain the truedeviation of the bullet at the proper moment. The difierently coloredimages stimulate the same nerves so there is no important reaction timeor lag in observations and the gunner and observer do not run the riskof losing sight of the projectile or target as would be the case wherethe signal is given by non- Visual means or where their vision isinterrupted.

For simple installations, as where there is a flank observer for eachgunner, the flank observer and gunner each follow the path of the samebullet as its trajectory appears to intersect the line of travel of thetarget, and when both the gunner and flank observer appear to see thetarget being hit at the time of the signal, the

gunner knOWs that his aim and range are both correct and that he hasmade a hit. If the gunner sees the bullet at any other point at theinstant of signal, the angular distance between the bullet and targetrepresents the true deviation and the gunner will correct his pointingaccordingly. The flank observer may operate the two observinginstruments simultaneously by means of a telegraph key and with only alittle practice he is able to anticipate the apparent intersection ofthe trajectory and target so as to eliminate his own reaction timeinvolved in closing the circuit after the intersection has apparentlyoccurred.

The observing instruments for the gunner and flank observer may be ofvarious widely different constructions, but as illustratively embodiedcomprise a pair of eyepieces or goggles to be worn by the gunner and asimilar pair to be worn by the observer. The goggles are provided withlenses which are of a relatively light color, each havin a smallaperture uncolored, said aperture lying in the line of vision of thecorresponding eye pupil. Another piece of the same colored materialoverlies the uncolored aperture, and is adapted to be moved into and outof overlying position by means of an electromagnet or solenoid. Thus,when the flank observer closes the circuit, the overlying pieces aremomentarily removed from their normal position and allow both men tohave a momentary uncolored view of the target and bullet, and thisactuation is rhythmically repeated as the trajectories of the bulletsappear to intersect the target.

While it is helpful for the flank observer to be provided with goggles,they are not essential for his observations, so that in simplest formthe apparatus will comprise a pair of goggles as described, Worn by thegunner or an observer at the gun position, while the flank observer mayuse only the naked eye or a cross-hair telescope and a manually operableswitch, such as a telegraph key, for closing the circuit.

Where mechanical means are provided for 7 closing the actuating circuit,means are provided for causing this closing to take place once each timea tracer bullet is fired, rather than once each time any kind of abullet is fired, and these means may comprise a switch adapted to beclosed only once each predetermined number of actuations, one actuationoccurring each time a bullet is fired, and the predetermined numbercorresponding to the relative number of tracers and bullets. In thepresent application, however, illustrative disclosure will be made onlyof a manually operable system, although it will be clear that mechanicalcircuit-closing means of the type referred to might be combinedtherewith.

It will be understood that the foregoing general description and thefollowing detailed description as well are exemplary and explanatory ofthe invention but are not restrictive thereof.

Referring now in detail to the illustrative embodiment of the presentinvention as shown by the accompanying drawings, there is provided acolor filter shifting device through which the gunner or observer at thegun station observes the path of the tracer bullet as well as thetarget, and this color filter shifting device is adapted to be operatedby means under control of the flank observer at a considerable distancefrom the gun. A similar color filter shifting device may optionally beprovided for the flank observer and this operates simultaneously withthe gunners device so that the observer and gunner may take theirobservations at precisely the same instant.

As embodied, the preferred form of color filter shifting devicecomprises a pair of goggles to be worn by the gunner, each of the gogglelenses being provided with or composed of a transparent color-filteringelement I i, which filter element is formed with a central clear spot oraperture I2 through which the tracer and target may be observed in theirnatural colors, while the surrounding area is viewed through the colorfilter. Preferably the color filter is of a light red or orange color soas to increase the contrast against the sky and to eliminate the haze asmuch as possible. However, the color of the filter may be varied to givethe best all-around visibility and to provide the maximum color contrastin the View of the tracer. The color filter I I may be conveniently usedas the cementing layer between two sheets of glass thus forming ashatter-proof or safety glass lens, A similarly colored filter shutterI3 is provided which is moved back and forth over the central apertureI2 in the lens, this movement being controlled by the flank observer,and as the clear central aperture is covered or uncovered by the shutterI3, the gunner receives his signal to take the observation of theposition of the tracer and target. Inasmuch as the signal is merely achange in color and the stimulus is transmitted to his brain over thatset of nerves which are already sensitized by the continuous vision,there is no appreciable reaction time involved and the readings are muchmore accurate than when an auditory or tactual signal is employed asmight otherwise be feasible. Furthermore the use of the color filterobstructs no part of the field of vision and thus allows the gunner andflank observer to watch the target and the entire flight of theprojectile (or as much thereof as desired) and when the signal is giventhe tracer and target are in full view and remain in full view.

The signal shutters are electromagnetically actuated and theelectromagnetic actuating means for the several pairs of goggles arepreferably connected in series so as to eliminate the necessity forusing matched lengths of wire and other circuit constants between thepower supply, signal transmitting and receiving stations. Whilepreferably both lenses II may be provided with the central uncoloredapertures I2 and corresponding filter shutters I3, if desired thisarrangement may be confined to only one lens of the goggles, the otherlens being entirely composed of the color filter layer I I.

The embodied means for electromagnetically actuating the filter shuttersI3 so as to cause them to rapidly uncover and recover the apertures I2comprises a centrally-disposed, pivotally mounted yoke I6, the arms I5of which extend toward the two lenses I I and in a plane just over theouter faces thereof. The two colored shutters I3 are rigidly fixed toeither end of the arms I5 of the yoke so as to normally cover theopenings I2. The shutters I3 are preferably relatively long and narrowrectangular strips of colored Celluloid or the like of a width somewhatgreater than the diameter of the corresponding apertures I2. The uppercentral portion I6 of the V-shaped yoke is pivotally mounted for limitedrotation so as to swing the shutters I3 to un cover the apertures I2 andthen to return them to the covered position. The eye pieces II aresuitably supported in circular frames 28 of metal or other suitablematerial. The frames are in tegrally formed with supporting arms 2|which extend upwardly and are pivotally connected by suitable bearingpins 23 near the ends of a rigid supporting frame 22. The frame member22 also serves to support the centrally disposed electromagneticmechanism which imparts turning movement to the shutter yoke I6. Asembodied, an electromagnet having a laminated iron core 25 is rigidlymounted centrally of the frame member 22 by a suitable bracket 26 heldby pins which pass through holes 26' in the frame. Thus that part of theframe and the electromagnet structure overlies the bridge of the nose ofthe wearer, as will be clear from Fig. 3. The electromagnet ispreferably rectangular, the opposed poles 21 and 28 being arcuate topermit close turning movement therebetween of the armature 29, the endsof which are conformably curved. The outer or base portion of the magnetis surrounded by a suitable electric coil 30, to which is connected alead wire 3|.

The embodied means for imparting movement from the rotatable armature 29to the arms l5 of the shutter yoke comprises a shaft 35, to the innersquare end 36 of which is fixed the central part I6 of the shutter yoke,so that the yoke will rotate with the shaft. The armature 29 surroundsthe shaft 35 and is fixed to rotate therewith as by pin 38. The outerend of shaft 35 is rotata-bly journaled in a suitable bearing bracket39, which bracket is fixed to the core of the electromagnet.

Means are provided for normally holding the armature 29 out of alinementwith the poles of the magnet, in which position the shutters I3 areadapted to cover the apertures l2. As embodied, the armature 29 ismounted to lie with its axis at an angle to the horizontal plane, asshown in Figs. 2 and '7, being held in that position by the end of aspring finger 49 which extends from a projecting finger 4| formed as apart of a bracket connected to and extending from the frame member 22.Upon energization of the magnet coil 39, the magnetic field will causethe armature 29 to rotate against the spring until it lies with its axishorizontal and it will there remain until the circuit is broken and thespring 41] returns it to its original position. Thus, closing of thecoil circuit will instantaneously cause the eyepiece apertures l2 to becleared by the shutters I3 and the re-closing of the shutters will beperformed just as rapidly by breaking the circuit.

The invention further comprises various means for adapting the pairs ofgoggles to the different sizes and configurations of the individuals whowill wear them. Primarily, the goggles are adapted for rapidly andsecurely varying the distance between the apertures I2 in a pair ofgoggles so as to accommodate them for various inter-pupillary distancescommonly encountered in human beings. As embodied, the arms 2| of thelens supports are provided with portions 5 which extend above thepivotal supporting shaft 23, and means are provided for impartingtransverse movement to said arms 59 to thereby cause a rocking movementof the frame 20 and thus a variation in the position of the centralapertures [2. For this purpose an internally threaded block or nut 5! ispivotally mounted to extend from the outer face of the arm 59, while athreaded shaft 52 passes through and engages the threads in said nut.The shaft 52 extends to engage similar nuts 5| on either arm 50 of thegoggles, it being clear, however, that the threading of the shaft andthe adjacent nut for the left-hand lens frame is opposite in directionto that for the right-hand, so that rotation of the shaft in a givendirection will cause the two lenses to move in opposite directions. Asuitable knurled knob 55 is provided at one end of the shaft and theshaft is further supported centrally in a U-shaped bearing bracket '56formed on and upstanding from the face of the main frame member 22. Thelead wire cable 3| for the magnet coil may also be supported by asuitable aperture in said bracket 56. It will be clear that rotation ofthe shaft 52 in the desired direction will cause the lenses H andapertures l2 to move together or spread apart the desired amount toaccommodate for variations in interpupillary distance of the wearer, andthe overlapping width and length of the shutter members 13 will besufficient to accommodate all such positional changes of the lenses andapertures.

The hereinbefore described goggle mechanism is preferably supported onthe head of the wearer by a suitable constricting brow band such as aleather or elastic strap 69, having means (not shown) for fastening sameat the rear of the wearers head. Preferably, also, a resilient metallicstrap 6! is adapted to engage and pass over the center line of thewearers skull, as in a telephone head set. The main frame 22 of thegoggles is suitably attached to the brow band 60 by means of a metalbrow strap 65 which is rigidly connected to the forehead portion of thebrow band as by rivets 66. A U-shaped bracket 61 extends outwardly fromthe band 65 and engages the inner faces of a conforming bracket 68struck up from the central portion of the main 'fram piece 22. s

The invention also provides for variations in the mounting and settingof the goggle mechanism to accommodate different shapes and slopes inthe configuration of the forehead of the wearer, so that, withinreasonable limits, the goggle lenses II will always lie substantiallynormal to the line of sight of the wearer. As embodied, the bracketmembers 61 are pivotally attached to the supporting brackets 69 by atransverse shaft 69 which permits rocking movement of the goggles andgoggle frame with respect to the forehead bracket 61. The bracketmembers 68 are also horizontally slotted at H! to permit a certainamount of fore-and-aft movement of the goggles and frame with respect tothe forehead. A tightening sleeve H is mounted about the projecting endof shaft 69 and is provided with an inclined slot 12 which cooperateswith a pin 13 on the shaft 69 to permit tightening of the shaft in anyposition of adjustment. A suitable tightening handle 14 may be providedto effect the desired action.

It will be understood that the foregoing detailed description anddisclosure of the goggle mechanism is merely illustrative of a preferredconstruction and means of adjustment thereof for carrying out the broadprinciples of the invention, and that numerous changes in construct onaldetails may and will be made in practice without departing from theessential features of the invention.

In operation, a pair of goggles, as indicated by MA in Fig. 1, will beworn by the gunner or an observer stationed at a machine gun G, whileanother pair of goggles IIB will be worn by a flank observer stationedat a suitable distance to the flank of the gun. As shown, the gogglesare connected in series by suitable lead wires and a suitable source ofpower such as battery 8| may be positioned at any convenient point inthe line. Normally, the circuit will be open whereby the gunner andobserver view the target and tracer bullets through the colored filtersI! and I3. 'A suitable manually operated switch 82, such as a telegraphkey which is adapted for rapid opening and closing, is placed at thehand of the flank observer. Upon the firing of a given tracer bulletboth the gunner and flank observer follow it with. their eyes throughthe color filters as it nears the aerial target. When the flank observersees that the bullet is about to intersect the line between himself andthe target, he closes the switch momentarily, thus causing thegunnersshutters E3 to open for a brief instant so that the gunner,looking through the clear space I2, will see the target and tracerbullet in their natural colors at the instant of intersection. The flankobserver will be able to gage his own reaction time so as to move toclose the switch sufiiciently early so that the gunner will receive theshutter signal at the instant of intersection, neither before nor after.It has been found that with a little practice the flank observer will beable to perform this operation very accurately at rates of fire of onetracer shot per second or even more rapidly.

In general the principles and objects of the invention may also berealized by causing the gun observer to normally view the projectile andtarget through an uncolored glass or with the naked eye and causing thecolor filter to move into his line of vision only at the instant ofsignalling. In that case the aperture 52 (which preferably would begreater in area) would normally be left open by keeping the circuitclosed, the filter shutter l3 being allowed to close only at the instantof signalling. Also the aperture I2 may be of a different color from thefilters II and E3, so that the change in the apparent color of theprojectile may be from one shade to another instead of from colored tonatural or vice versa.

The general construction of the observing goggles may also be utilizedto carry out the principles of the fire observation and control with anopaque shutter as disclosed and claimed in the previously mentionedapplication of Grayson Schmidt Ser. No. 79,822. That is, the desiredsignal may be imparted to the gun observer by causing an opaque shutterto flash across his line of vision at the desired instant, his visionbeing otherwise normal and uncolored. For such use the lenses H of thegoggles may be of clear glass throughout, while an opaque shuttersimilar to the shutter l3 would normally be mounted outside the line ofdirect vision of the wearer. If preferred the clear glass lens may beomitted so that the observer normally looks through an empty frame. Atthe instant of signaling said opaque shutter would be caused to crossthe observers line of vision and immediately recede therefrom. Byproviding a speed shutter movement across the line of vision faster thanT 'g second the persistence of vision will not be interrupted, but theobserver will receive a distinct impression or signal to his opticalnerves. This signaling effect will be similar to that shown anddescribed in connection with the magnetic shutter mechanism in saidSchmidt application.

While the invention has been illustrated with one gun observer undercontrol of a flank observer, it is possible to so coordinate the firingsof several guns that they may be under the control of a single flankobserver without imposing an undue burden on, the flank operator. Thiscoordination will consist primarily in the suitable spacing of tracer.bullets for the several guns so that they fire in sequence and atintervals no smaller than say one-third a second.

A modification of the lens construction (not shown) may be provided,wherein one or both lenses of the goggles may be provided with verticaland/or horizontal cros hairs and also with mil scale divisions tofacilitate observation of fire.

The invention in its broader aspects is not limited to the specificmechanisms shown and described but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciples of the invention and without sacrificing its chiefadvantages.

What we claim is:

l. Mechanism for controlling fire of a gun using projectiles which arevisible for at least a portion of their trajectory, including incombination, a color filter transparency, means for maintaining saidcolor filter in the line of vision of an observer at the gun for viewingthe target and trajectory of said projectile, electrically-operatedmeans for suddenly removing said filter from the line of vision of theobserver to inform him when the projectile has reached a selected pointon its trajectory, a switch at a flank position and circuit connectionstherefrom to the electricallyoperated means for controlling the movementof the filter from a flank position.

2. Mechanism for observing a gun projectile having a visible trajectoryincluding in combination a colored transparency positionable in the lineof vision of an observer at the gun and means for controllably removingsaid colored transparency from said line of vision and for restoringsame to said line of vision comprising an electrically-operated actuatorfor moving said transparency, circuit connections and a switch forcontrolling said movements from a remote station and a similar coloredtransparency at said remote station and, an electrically operatedactuator therefor, said actuators being connected in series.

3. In an apparatus for observing and controlling gun fire thecombination of a pair of goggles comprising lenses and means forsupporting said lenses on an observer's head in hisline of vision, saidlenses being covered for the most part with a color filter but having aclear spot directly in the line of vision, and a colored member movablerelatively to the clear spot to cover and uncover same.

4. In an apparatus for observing and controlling gun fire thecombination of a pair of goggles comprising lenses, means for supportingsaid lenses from on an observers head in his line of vision, said lensesbeing covered for the most part with a color filter but having a clearspot directly in the line of vision, a colored member movable relativelyto the clear spot to cover and uncover same and electromagnetic means onthe supporting means for moving said colored memher.

5. Mechanism for fire observation and control including in combination apair of viewing lenses adapted to be positioned before the eyes of anobserver, means for fastening said lenses in said position on the headof the observer, a color filter transparency normally lying in the lineof vision of the observer, and electromagnetic means for moving saidcolored transparency out of said line of vision.

6. Mechanism for fire observation and control including in combination apair of viewing lenses adapted to be positioned before the eyes of anobserver, means for fastening said lenses in said position on the headof the observer, a color filter transparency normally lying in the lineof vision of the observer through at least one of said lenses,electromagnetic means for moving said colored transparency out of saidline of vision, a second pair of lenses similarly constructed for asecond observer, and circuit means connecting the electromagnetic meansof each pair so that the transparencies may be moved simultaneously.

'7. Mechanism for fire observation and control including in combinationa pair of viewing lenses adapted to be positioned before the eyes of anobserver, means for fastening said lenses in said position on the headof the observer, a color filter transparency on at least one of saidlenses and normally lying in the line of vision of the observer,electromagnetic means for moving said colored transparency out of saidline of vision, and means for varying the interpupillary distance of thetwo lenses.

8. Mechanism for controlling fire of a gun using tracer projectilesincluding in combination a color filter transparency movably mountedacross the line of vision of an observer at the gun for viewing thetarget and trajectory of a projectile, means for moving said filter intoand out of said line of vision to vary the view of the observer, anunobstructed view being obtained when the filter is out of the line ofsight, and means at a locus remote from the observer for controlling theactuation of said filter-moving means to inform the observer when theprojectile has reached a selected point on its trajectory by varying thecolor of his field of view.

9. Mechanism for controlling fire of a gun using tracer projectilesincluding in combination a color filter transparency movably mountedacross the line of vision of an observer at the gun for viewing thetarget and trajectory of a projectile, electrically operated means formoving said filter into and out of said line of vision to vary the viewof the observer, and means at a locus remote from the observer forcontrolling the actuation of said filter moving means to inform theobserver when the projectile has reached a selected point on itstrajectory by varying the color of his field of view, said meanscomprising devices for transmitting electrical energy from said locus tosaid filter-moving means.

GEORGE B. FINNEGAN, JR. HOBART N. DURHAM.

